<!doctype HTML>
<style>
.target {
    -webkit-mask: url(../../animations/resources/stripes-100.png);
}
legend {
    height: 12px; width: 50px;
    background-color: blue;
    padding: 0;
}
</style>
<!-- Should show a blue rect for the legend, that looks dotted due to the striped mask. -->
<fieldset class="target">
    <legend></legend>
</fieldset>